Various types of materials are made and rolled into relatively large cylindrical coils for shipment to purchasers who use the materials to make products. While some materials (such as wires) are rolled on spools, many materials are not rolled on spools and, in such cases, the coils typically have a central cylindrical opening that is defined by the material itself. Example materials include papers and metals (such as steel, aluminum, and tin).
More specifically, for example, the steel industry makes sheet steel and rolls the sheet steel into coils (with central cylindrical openings) for use by various manufacturers (such as automobile and automobile part manufacturers). Steel sheets are typically rolled on a mandrel during the final phase of manufacture. These mandrels typically have a diameter of 20 or 24 inches. These steel coils are extremely heavy and typically weigh between 30,000 and 80,000 pounds. Two, three, four, or more steel straps are typically placed through the central opening and wrapped around the outside of the steel coil to prevent the steel coil from uncoiling or unrolling during storage and transport of the steel coil. Steel coils are also sometimes wrapped in paper or plastic to protect the steel coils during storage and transport of the steel coils.
Cranes (such as overhead cranes) are often employed to transport or maneuver these large coils in the manufacturing facilities and in the production or use facilities (following their delivery to customers). These cranes typically have a generally L-shaped or C-shaped hook or engaging implement (such as a tong or tongue) that is positioned inside the central cylindrical opening of the coil and that engages the upper portion of the inner surface that defines the central opening of the coil. These hooks are commonly used to engage, lift, and move the coils in the coil manufacturing facilities and in the coil use facilities, particularly when the coils are loaded into and unloaded from transport vehicles, such as trucks and freight railroad cars. The hook is typically inserted into one end of the central opening of the coil and is then raised to engage the upper portion of the inner surface that defines the central cylindrical opening of the coil to lift the coil and to move the coil to the desired location. The hook can damage the material of the coil, particularly by bending the edges of the material of the coil that define or that are located adjacent to the central opening of the coil. For example, when the hook is placed through the central opening of the coil and raised upwardly into engagement with the upper portion of the inner surface that defines the central opening, the hook may not simultaneously, evenly, or with equal pressure engage that upper surface at both opposite edges that define the central opening. Instead, the hook may first engage one edge and then the other. When this happens, the pressure of the hook on the material can cause bending or other damage to the material of the coil that defines or that is adjacent to the central opening. This bent material is typically not usable. In steel coils, it is not uncommon for the material user to have to scrap several feet of the sheet steel due to such damage.
In addition to the damage that can be caused by the hook during loading and unloading of the coils, transporters often throw a chain through the central opening of the coil to secure the coil on the transport vehicle (such as a truck or a freight railroad car). This chain can also damage the inner surfaces that define the central opening of the coil or the surfaces that are adjacent to the central opening of the coil.
Plastic coil protectors have been employed to solve these problems. For example, U.S. Pat. No. 4,513,864 and U.S. Pat. No. 6,783,833 disclose plastic coil protectors that are configured to protect the material that defines the central opening of the coil and the material of the coil adjacent to the central opening. These coil protectors are typically strapped in place as shown in FIG. 1 of U.S. Pat. No. 4,513,864. In some instances, wrapping machines are employed to wrap both the coil and the coil protectors with a paper or shrink wrap covering.
While these known coil protectors generally protect the coils, they create additional problems.
For example, these known coil protectors are made in separate plastic manufacturing facilities and then shipped to coil manufacturing facilities. These known coil protectors are relatively large and bulky; have fixed circumferences and diameters; and, when they are stacked for storage and transport, they take up a considerable amount of space. Substantial space must be provided at the plastic manufacturing facilities, in the transport vehicles, and at the coil manufacturing facilities for these known coil protectors. After these known coil protectors are used and are no longer needed at the coil material use facilities, they are sometimes stored and shipped back to the coil manufacturing facilities. This storage and transport cost is also very high because these known coil protectors are relatively large and bulky. In some instances, these known plastic coil protectors are recycled. In other instances, partly due to their size, these known plastic coil protectors are placed in the garbage and not recycled. In such instances, these known coil protectors take up substantial space in landfills.
Another problem with these known coil protectors is that they do not account for variations that occur in the sizes of the central openings of the coils. For example, as mentioned above, sheet steel coils are typically formed on two different size mandrels and typically have two different size openings (i.e., 20 inch and 24 inch openings). The known coil protectors do not account for these different size openings and, therefore, sheet steel coil manufacturers must maintain two different size coil protectors in inventory. This creates extra storage and inventory tracking requirements. Additionally, when the coils are made on each mandrel, manufacturing tolerance variations tend to cause the central openings to be of slightly different sizes. For example, coils made on a 20 inch mandrel may have a 20.1 inch diameter central opening or a 20.5 inch diameter central opening. These different size openings tend to cause the known coil protectors to not snugly fit in certain coils with slightly larger size central openings due to variations in manufacturing tolerances. Likewise, when the known coil protectors are made, manufacturing tolerance variations can cause variations in the circumferences or diameters of these known coil protectors, which can lead them to not fit the coils as desired.
Accordingly, there is a need for new coil protectors that solve these problems.